实验环境
数据库选择的是orclpdb1，当前系统表空间未加密：
SQL> show con_nameCON_NAME
------------------------------
ORCLPDB1SQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from dba_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE NO
SYSAUX ONLINE NO
UNDOTBS1 ONLINE NO
TEMP ONLINE NO
USERS ONLINE NO
加密
在线加密系统表空间：
SQL> alter tablespace system encryption online encrypt;Tablespace altered.SQL> alter tablespace sysaux encryption online encrypt;Tablespace altered.SQL> alter tablespace undotbs1 encryption online encrypt;Tablespace altered.SQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from dba_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE YES
SYSAUX ONLINE YES
UNDOTBS1 ONLINE YES
TEMP ONLINE NO
USERS ONLINE NO
就剩下临时表空间了，按照文档3.6.1 About Encryption Conversion for Tablespaces and Databases中表Table 3-2 Offline and Online Tablespace and Database Encryption Conversions的说明，在线和离线加解密都不可行：
SQL> alter tablespace temp encryption online encrypt;
alter tablespace temp encryption online encrypt
*
ERROR at line 1:
ORA-28370: ENCRYPT, DECRYPT or REKEY option not allowed
对于临时表空间，只能新建一个加密的临时表空间，然后指定其为默认临时表空间。过程如下。
首先从SQL Developer中得到当前临时表空间的SQL：
SQL>
CREATE TEMPORARY TABLESPACE "TEMP" TEMPFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/temp01.dbf' SIZE 246415360AUTOEXTEND ON NEXT 655360 MAXSIZE 32767MEXTENT MANAGEMENT LOCAL UNIFORM SIZE 1048576;
然后新建加密的临时表空间：
CREATE TEMPORARY TABLESPACE "TEMP_TDE" TEMPFILE 'temp01_tde.dbf' SIZE 246415360 AUTOEXTEND ON NEXT 655360 MAXSIZE 32767MEXTENT MANAGEMENT LOCAL UNIFORM SIZE 1048576ENCRYPTION ENCRYPT;Tablespace created.SQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from dba_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE YES
SYSAUX ONLINE YES
UNDOTBS1 ONLINE YES
TEMP ONLINE NO
USERS ONLINE NO
TEMP_TDE ONLINE YES6 rows selected.
当前默认的临时表空间：
SQL>
col PROPERTY_NAME for a40
col PROPERTY_VALUE for a10
col DESCRIPTION for a40
set lines 120
select * from database_properties where property_name like 'DEFAULT%SPACE%';PROPERTY_NAME PROPERTY_V DESCRIPTION
---------------------------------------- ---------- ----------------------------------------
DEFAULT_PERMANENT_TABLESPACE USERS Name of default permanent tablespace
DEFAULT_TEMP_TABLESPACE TEMP Name of default temporary tablespace
设置新的临时表空间，删除老的临时表空间：
SQL> alter database default temporary tablespace temp_tde;Database altered.SQL> drop tablespace temp including contents and datafiles;Tablespace dropped.SQL> select * from database_properties where property_name like 'DEFAULT%SPACE%';PROPERTY_NAME PROPERTY_V DESCRIPTION
---------------------------------------- ---------- ----------------------------------------
DEFAULT_PERMANENT_TABLESPACE USERS Name of default permanent tablespace
DEFAULT_TEMP_TABLESPACE TEMP_TDE Name of default temporary tablespaceSQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from dba_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE YES
SYSAUX ONLINE YES
UNDOTBS1 ONLINE YES
USERS ONLINE NO
TEMP_TDE ONLINE YES
解密
解密当然也可以在线，但为了涵盖加解密功能，此处使用离线解密。
实例运行时，offline是不行的：
SQL> alter tablespace system offline;
alter tablespace system offline
*
ERROR at line 1:
ORA-01541: system tablespace cannot be brought offline; shut down if necessary
需要关闭数据库：
SQL> shutdown immediate
Pluggable Database closed.SQL> show pdbsCON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------3 ORCLPDB1 MOUNTED
此时表空间已经离线了，可以解密：
SQL> alter tablespace system encryption offline decrypt;Tablespace altered.SQL> alter tablespace sysaux encryption offline decrypt;Tablespace altered.SQL> alter tablespace undotbs1 encryption offline decrypt;Tablespace altered.
临时表空间还是同样的问题，不能直接解密：
SQL> alter tablespace temp_tde encryption offline decrypt;
alter tablespace temp_tde encryption offline decrypt
*
ERROR at line 1:
ORA-28370: ENCRYPT, DECRYPT or REKEY option not allowed
启动数据库，目前状态如下：
SQL> alter database open;Database altered.SQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from user_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE NO
SYSAUX ONLINE NO
UNDOTBS1 ONLINE NO
USERS ONLINE NO
TEMP_TDE ONLINE YES同前例，创建一个新的未加密的临时表空间，然后取而代之：
CREATE TEMPORARY TABLESPACE "TEMP" TEMPFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/temp01.dbf' SIZE 246415360AUTOEXTEND ON NEXT 655360 MAXSIZE 32767MEXTENT MANAGEMENT LOCAL UNIFORM SIZE 1048576;alter database default temporary tablespace temp;drop tablespace temp_tde including contents and datafiles;
现在，全部解密了：
SQL> select TABLESPACE_NAME, STATUS, ENCRYPTED from user_tablespaces;TABLESPACE_NAME STATUS ENC
------------------------------ --------- ---
SYSTEM ONLINE NO
SYSAUX ONLINE NO
UNDOTBS1 ONLINE NO
TEMP ONLINE NO
USERS ONLINE NO
参考
- Oracle Temporary Tablespace
- ORA-01541: System Tablespace Cannot Be Brought Offline; Shut Down If Necessary
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